1. Field of the Invention
The invention relates to a lock for locking the steering shaft or the gear rack of the steering gear or the output shaft of the transmission of a motor vehicle, said lock being fitted with a locking element displaceable to-and-fro between a locked and an unlocked position, and further with a control element rotated to-and-fro by means of a drive to axially displace a drive element cooperating with the locking element or to displace the locking element itself in either direction.
2. Description of the Related Art
A lock of this kind is known, wherein special steps are taken to assure that the locking element always shall move exactly the same distance to the locked or unlocked position but not farther, not even when the control element continues rotating, that is even when the drive is not stopped at the moment when the locking element has reached the locked or unlocked position. For that purpose the drive element or the locking element and the control element are configured coaxially, and said drive element or the locking element and the control element cooperate by means of
(a) two radial projections which are diametrically opposite the axis of rotation of the control element and are each displaceable as well as spring-loaded perpendicularly to the control element""s axis of rotation,
(b) two bevels as well as two terminal surfaces which are situated in the same plane perpendicular to the control element""s axis of rotation and can extend as far as next to either bevel, in such manner that the inner drive element or the inner locking element shall be commensurately axially displaced during the rotation of the outer control element in that direction in which the protrusions run on the bevels to the terminal surfaces, in order that, when the projections move from the bevels onto the terminal surfaces, they shall stand still and remain in the attained axial position until the control element is rotated in the opposite direction and the protrusions move on the bevels away from the terminal surfaces, whereby the drive element or the locking element shall be shifted axially in the opposite direction. These protrusions may be situated at the drive element or the locking element, and the bevels and the terminal surfaces may be located on the control element. The protrusions, if desired, may comprise two pins mounted in a common transverse borehole of the drive element or the locking element and may be biased by a common helical compression spring (see German Patent No. DE 44 36 326 C1).
The objective of the invention is to improve said known lock and in particular to reduce the number of parts, to simplify assembly and to lower manufacturing costs.